Internal amide, nonpolymeric thioether sensitizers for photographic emulsions



United States Patent 3,057,724 INTERNAL AMIDE, NONPOLYMERIC THIO- ETHER SENSITIZERS FOR PHOTOGRAPHIC EMULSIONS William G. Lovett, Peter I. Chiesa, and John R. Dann,

Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Dec. 11, 1959, Ser. No. 858,872 13 Claims. (Cl. 96-108) This invention relates to photographic silver halide emulsions, and more particularly, to an improved means for sensitizing such photographic silver halide emulsions.

A number of methods have been previously described for increasing the sensitivity of photographic silver halide emulsions, other than methods of optical or spectral sensitization, which involve the incorporation of certain colored compounds or dyes in the emulsions. The incorporationof such dyes in the emulsions increases the optical range of sensitivity, and for this reason such dyes are commonly referred to as optical or spectral sensitizing dyes. It is also well known to increase the sensitivity of photographic emulsions by addition of sulfur compounds capable of reacting with silver salts to form silver sulfide, ,or with reducing agents (compounds of these types are also naturally present in gelatin), or with salts of gold or other noble metals, or with combinations of two or more of the aforementioned compounds generally known as chemical sensitizers. Such chemical sensitizers are belived to react with the silver halide to form, on the surface of the silver halide, minute amounts of silver sulfide or of silver or of other noble metals, and these processes are capable of increasing the sensitivity of developingout emulsions by very large factors. The process of chemical sensitization, however, reaches a definite limit beyond which further addition of sensitizer, or of further digestion with the sensitizer present, merely increases the fog of the photographic emulsion with constant or decreasing speed.

We have now found a means of further increasing the sensitivity of photographic emulsions which may be applied even though the ordinary processes of chemical sensitization have been carried to the effective limit of the photographic emulsion in question. Our process is to be distinguished from hypersensitization, which is produced by bathing a finished coating with water or with solutions of ammonia, amines or silver salts. Such processes act primarily on optically sensitized photographic emulsions and tend to increase the free silver ion concentration of the emulsion and greatly diminsh its stability. Our process is also to be distinguished from hypersensitization by mercury vapor, which gives a transitory effect which is lost on storage of the film. The compounds used in our invention do not appear to be chemical sensitizers in the usual sense, since they increase speed by their presence during exposure and processing and require no digestion with the photographic emulsion to produce an increase in speed, nor does their chemistry seem to indicate that they are likely to react with silver halide under normal emulsion conditions.

The novel sensitizers of our invention are quite unique in that the effects produced are additive in photographic emulsions which have already been sensitized to their optimum, or near-optimum, with conventional chemical sensitizers, such as labile sulfur compounds. The novel sensitizers of our invention, however, can he used to sensitize photographic silver halide emulsions containing no other sensitizers, if desired. The novel sensitizers of our invention are not strictly chemical sensitizers, since chemical sensitizers do not generally provide the additive effects of the type mentioned.

It is, therefore, an object of our invention to provide "ice photographic silver halide emulsions which have been sensitized with various non-polymeric compounds containing a plurality of sulfur atoms. Another object of our invention is to increase the sensitivity of ordinary photographic silver halide emulsions whichhave been sensitized with chemical sensitizers, such as compounds containing labile sulfur atoms, or gold-containing compounds. Other objects will become apparent from a consideration of the following description and examples.

According to our invention, we have found that the sensitivity of an ordinary photographic silver halide emulsion can be materially increased by incorporating therein certain non-polymeric compounds which can be characterized as thioethers containing internal amide linkages. By thioether, we mean a linkage wherein the sulfur atom is divalent and is joined to two non-oxocarbonylic carbon atoms. Compounds useful in sensitizing photographic silver halide emulsions according to the present invention are to be distinguished from the polymeric thioether compounds described in U.S. Patent application Serial No. 779,874, filed December 12, 1958, by I. R. Dann and J. J. Chechak. The polymeric compounds described in this latter application are generally characterized as having high molecular weights and as containing characteristic sulfur-containing repeating units or groups.

The sensitizing compounds useful in practicing our invention are non-polymeric and can be represented by the following general formula:

wherein R represents a methylene group, a substituted methylene group (e.g., methyl-substituted, ethyl-substituted, propyl-substituted, isopropyl-substituted, etc., methylene groups) or a p,p'-hexahydroxylylenyl group .(i.e., a cyc1ohexylene-p,p'-bismethylene group), R represents a hydrogen atom or a methyl group and R represents an alkyl group, such as methyl, ethyl, propyl, butyl, etc., an alkoxyalkyl group, such as methoxyethyl, ethoxyethyl, butoxyethyl, methoxypropyl, etc., an alkoxyalkoxy-alkyl group, such as ethoxyethoxyethyl, methoxyethoxyethyl, etc., a hydroxyalkyl group, such as B-hydroxyethyl, 'y-hydroxypropyl, etc., a hydroxyalkoxyalkyl group, such as B-hydroxyethoxyethyl, y-hydroxypropoxyethyl, etc., a hydroxyalkoxyalkoxyalkyl group, such as B-hydroxyethoxyethoxyethyl, y-hydroxypropoxypropoxyethyl, etc., or an aryloxyalkyl group, such as fi-phenoxyethyl, 'y-phenoxypropyl, etc.

Another group of useful sensitizing compounds embraced by our invention is that represented by the following general formula:

wherein R and R each have the values given above and R represents either two hydrogen atoms or a propen-lylidene-3 group.

The compounds of Formulas I, II and III can be prepared according to methods illustrated below. Certain of these compounds can be prepared by the addition of a mercaptan compound across an olefinic double bond. Compounds containing a hydrazine group can be prepared by condensing hydrazine with the product resulting from the condensation of a carbethoxythiol compound across an dlefinic double bond, while hydrazide compounds can be prepared by condensing the hydrazine compounds with an aldehyde, such as acrolein. These general methods can be illustrated as follows:

Method A.-The addition of a rnercaptan across an olefinic double bond, e.g.,

Method B.The reaction of an alkyl halide with a thiolacetate compound in the presence of sufiicient alkali to hydrolyze the thiolacetate to a rnercaptan and, if desired, simultaneously effect its reaction with the alkyl halide. This allows the reaction to proceed without the isolation of the free rnercaptan with its attendant difiiculties of purification and danger of oxidation to a disulfide, e.g.,

Method C.The reaction of hydrazine with compounds containing thioether groups and having ester end groups, e.g.,

Method D.-The reaction of hydrazides of the type shown in Method C with aldehydes or ketones, e.g.,

I CH2=CHCH=N--NH-CCHr-S to each end of the open chain compound.

The following examples will serve to illustrate the preparation of typical compounds which can be used in sensitizing photographic emulsions according to our invention.

EXAMPLE 1 7,9-Diaza-I,15-Dihydroxy-3,13-Dithiapentadecane- 6,10-Dione ll (HO CHzCHzSCHzCHrC-NHhCH Methylene bis acrylamide, 7.7 g. (0.05 mole), and 2- mercaptoethanol, 7.8 g. (0.10 mole), were dissolved in 50 ml. of absolute ethanol containing 10 drops of a 30% methano'lic solution of benzyl trimethylammonium hydroxide. The reaction mixture was heated for 2 hours on the steam bath under a reflux condenser. The product was filtered from the cooled reaction mixture and recrystallized from ethanol. M.P. 17l173 C.

Anaylsis.-Ca1cd. for C11H22N2S204I C, H, S, 20.6; N, 9.0. Found: C, 42.5; H, 6.9; S, 20.6; N, 8.7.

EXAMPLE 2 J0,12-Diaza-3,19-Dioxa-6,16-Dithiaheneic0sane-9,1 3 Dione Reaction of methylene bis acrylamide thiolacetate and ethoxyethyl bromide: CH COSCH CH CONHCH NHCOCH CH SCOCH CH CH OCH CH SCH CH CONHCH NHCOCH CH SCH CH OCH CH In 300 ml. ethanol were dissolved 4.4 g. of methylene bis acrylamide thiolacetate (0.0144 mole) (prepared as described in Example 1 from methylene bis acrylamide and thiolacetic acid) and 6.1 g. ethoxyethyl bromide (0.04 mole). To this were added 4.2 g. of sodium carbonate (0.04 mole) dissolved in 250 ml. of distilled water. After refluxing 6 hours, the mixture was chilled and the white crystals formed were filtered and dried. The yield of product recrystallized from ethanol was 3.45 g. and the melting point was 166167 C.

Analysis.Calcd. for C H N S O C, I'I, S, 17.5; N, 7.7; mol. wt, 366. Found: C, 49.4; H, 7.8; S, 17.4; N. 8.0; mol. wt., 326.

EXAMPLE 3 13,15-Diazo-3,6,22,25-Tetr0xa-9,19-Ditlziaheptacosane- 12,16-Di0ne Reaction of methylene bis acrylamide thiolacetate and ethoxyethoxyethyl bromide:

CH COSCH CH CONHCH NHCO CH CH SCO CH CHZCHZOCHZCHZBI'Q CH CH OCH CH OCH CH SCI-I CH CONH CH This compound was made by the same general method as Example 2. The melting point was 129-131 C.

Arzalysis.Calcd. for C H N S O C, 50.3; H, 8.4; S, 14.1; N, 6.2; mol. wt., 454. Found: C, 50.2; H, 8.2; S, 14.3; N, 6.6; mol. wt., 471.

EXAMPLE 4 9,1 0-Diaz0-2,18-Dioxa-5,15-Dithianonadecane-8,1 2- Dione Reaction of methylene bis acrylamide thiolacetate and methoxyethyl bromide:

O I ll (CHaSOHBOHzCNHhCH: ZOHQO 01110112131 H (CHsO CHzOHzSCH CH CNHhCH;

This compound was made by the same general method as Example 2. The melting point was 129-131 C.

Analysis.Calcd. for C H N S O C, 46.1; H, 7.7; S, 18.9; N, 8.3; mol. wt., 338. Found: C, 46.2; H, 7.7; S, 19.2; N, 8.6; mol. wt., 332.

EXAMPLE 5 Preparation of the dihydr-azide of 6,8-diaza-1,13-dicarboxy-Z,12-dithiatridecane-5,9-dione:

The reaction product obtained by adding 0.2 mole of ethylmercaptoacetate to 0.1 mole of methylene bis acrylamide was heated in 75 ml. of 64% hydrazine hydrate for one hour on the steam bath under a reflux condenser. After standing for 2 days at room temperature, white crystals were formed. These were washed with water and recrystallized from ethanol to give a product melting at 199201 C.

Analysis.Calcd. for C H S N O C, 36.1; H, 6.0; N, 22.9; S, 17.5. Found: C, 36.0; H, 5.9; N, 22.9; S, 17.3.

EXAMPLE 6 Preparation of 4,5,12,14,21,22 hexazo 8,18 dithia- 1,3,22,24pentacosatetraene-6,11,15,20-tetrone:

Acrolein, 0.23 g. (0.004 mole) and the dihydrazide of 6,8 diaZ-a 1,13 dicarboxy-Z,l2-dithiatridecane-5,9- dione, 0.72 g. (0.002 mole) were dissolved in 37 ml. of water and 12 ml. of ethanol. The reaction mixture was heated on the steam bath for 45 minutes and the white precipitate was filtered off and washed with ethanol. The melting point was 260 C. dec.

Analysis.-Calcd. for C17H26N6S2O4Z C, 46.1; H, 5.9; N, 19.0; S, 14.5. Found: C, 46.5; H, 6.2; N, 19.4; S, 14.8.

EXAMPLE 7 8,10-Diaza-1,1 7-Dihydroxy-4,14-Dithiaheptaziecane- 7,1 1 -Dine Reaction of methylene bis acrylamide thiolacetate and 3 bromo-1-propanol 0 (CHa SCH2CHz( JNH)zOHz 2110 CHQCEQGHZBI 0 (HO OHZOEHOHQSOHZOHZ NHhCH This compound was made by the same general method as Example 2. The melting point was 163-165 C.

Analysis.-Calcd. for C H S N O C, 46.2; H, 7.7; S, 18.9; N, 8.3. Found: C, 46.2; H, 7.8; S, 19.1; N, 8.6. EXAMPLE 8 10,12-Diaza-3,19-Di0xa-1 ,2] -Diphen0xy-6,1 6- Di thiaheneicosan e-9,1 3-Di0ne (CH COSCH CH CONH) CH +2ClCl-I CH 0CH CH OC H (C H OCH CH OCH CH SCH CH CONH) CH Reaction of methylene bis acrylamide thiolacetate and phenoxyethoxyethyl chloride:

This compound Was made by the same general method as Example 2. MP. 203-210 C.

Analysis.Calcd. for C H N S O C, 59.0; H, 6.9; N, 5.1; S, 11.9. Found: C, 57.6; H, 6.8; N, 6.0; S, 12.1. EXAMPLE 9 7,9-Diaza-3,13-DithiapentadecanefiJO-Dione Reaction of methylene bis acrylamide and ethanethiol:

(CH2 JJOONHhCHz ZHSCHzCHzOOHzCHa CH3 This compound was made by the same general method as Example 1. M.P. 82 C.

Analysis.Calcd. for C18H32N2S2O4: C, H, N, 7.1; S, 16.2. Found: C, 51.8; H, 8.6; N, 6.8; S, 16.1.

EXAMPLE 11 10,12-Diaza-11-Is0pr0pyl-3,19-Di0xa-6,16-Dithiaheneic0sane-9,13-Di0ne Reaction of isopropyl N,N-(methylene bis acrylamide) and Z-mercaptoethoxy ethane:

(CHFCHCONIEDzCHCHCBk 2HSOH2GH2OGH2GH3 This compound was made by the same general method as Example 1. M.P. 9799 C.

Analysis.Calcd. for C H N S O C, 52.8; H, 8.8;

N, 6.9; S, 15.7. Found: C, 53.0; H, 8.9; N, 7.0; S, 15.8.

EXAMPLE 12 Bis-1,4-(Ethoxyethylmercaptoethylcarbonylamidom'ethyl) Cyclohexane Reaction of bis-1,4-(chloroethylcarbonylamidomethyl)- cyclohexane and Z-mercaptoethoxyethane:

ClCHzCHaC ONHCHr E -CH2NHU 0 (3112013201 011301120 OHzCHzSCHzOHgC ONHOHr- S OHzNHCOOHzGHgSCHaOHzOOHzCH;

This compound was made -by refluxing the above ingredients for 7 hours, evaporating the solvents and extracting the desired product with hot absolute ethanol. Upon cooling, the precipitate obtained was filtered and recrystallized from ethanol. M.P. 157-159 C.

Analysis.Calcd. for C H N S O C, 57.1; H, 9.1; N, 6.1; S, 13.8. Found: C, 56.9; H, 9.2; N, 5.7; S, 13.9.

EXAMPLE 13 Preparation of his 1,4-(chloroethylcarbonylamidomethyl)cyclohexane (intermediate for Example 12):

Nnzonwonmm 2o1om01-12ooo1 01011201120 oernonQ-onmno 0 0112011201 HCI OH; HCHO 2CH =CHCONH2 One mole of acrylamide (71 g.) and 0.5 mole of isobutyraldehyde (36 g.) were dissolved in 70 ml. distilled Water and 60 ml. concentrated hydrochloric acid. The mixture was warmed to 3035 C. for 15 minutes, then cooled, the product filtered off, and recrystallized from ethanol. The yield of material was 44 g. M.P. 270 C.

Analysis.-Calcd. for C10H1602N2 C, H, N, 14.3. Found: C, 60.9; H, 8.1; N, 13.9.

The sensitizing compounds of our invention can be added to ordinary photographic silver halide emulsions for the purpose of increasing the sensitivity thereof, as has been indicated above.

The preparation of photographic silver halide emulsions involves three separate operations: 1) emulsification and digestion of silver halide, (2) the freeing of the emulsions of excess water-soluble salts, usually by washing with water, and (3) the second digestion or afterripening to obtain increased emulsion speed or sensitivity (Mees, The Theory of the Photographic Process, 1954). The sensitizers of our invention can be added to the emulsion before the final digestion or after-ripening, or they can be added immediately prior to the coating. Our new photographic sensitizers require no special final digestion or after-ripening.

The particular quantity of sensitizer used in a given emulsion can vary, depending upon the effects desired, degree of ripening, silver content of the emulsion, etc. The amount used is also dependent upon the particular stage at which the sensitizer Was added during the preparation of the emulsion. We have found that generally from about 50 mg. to about 5 g. of sensitizer per mole of silver halide are quite adequate to accomplish the desired sensitization.

The sensitizers of our invention can be added to photographic emulsions using any of the Well known techniques in emulsion making. For example, the sensitizers can be dissolved in a suitable solvent and added to the silver halide emulsion, or they can be added to the emulsion in the form of a dispersion similar to the technique used to incorporate certain types of color-forming compounds (couplers) in a photographic emulsion. Techniques of this type are described in Jelley et al. U.S. Patent 2,322,027, issued June 15, 1943, and Fierke et al. U.S. Patent 2,801,171, issued July 30, 1957. As indicated above, the solvent should be selected so that it has no harmful eifect upon the emulsion, and generally solvents or diluents which are miscible with water are to be preferred. Water or dilute alkali is a dispersing medium for some of the sensitizers of the invention. In a preferred embodiment, the sensitizers can be dissolved in a solvent, such as ethanol, acetone, pyridine, N,N-dimethylformamide, etc., and added to the emulsion in this form. If desired, certain of the sensitizers can be prepared in finelydivided form and dispersed in water alone, or in the presence of a suitable dispersing agent (such as alkali metal salts of aromatic or aliphatic sulfonic acids) and added to the emulsion in this form. It is quite apparent that the sensitizers of our invention should have suflicient water-dispersibility so that they can be adsorbed to or associated with the grains of the silver halide present in the emulsion in sufiicient amount to sensitize the emulsion. It is apparent that the optimum amount for each of the sensitizers will vary somewhat from emulsion to emulsion and from compound to compound. The optimum amount of any given sensitizer can be determined from any particular emulsion by running a series of tests in which the quantity of sensitizer is varied over a given range. Exposure of the treated emulsion in conventional photographic testing apparatus, such as an intensity scale sensitometer, will reveal the most advantageous concentrations for that sensitizer in that particular emulsion. Such matters are well understood by those skilled in the art.

The photographic emulsions used in practicing our invention are of the developing-out type.

The emulsions can be chemically sensitized by any of the accepted procedures. The emulsions can be digested with naturally active gelatin, or sulfur compounds can be added such as those described in Sheppard US. Patent 1,574,944, issued March 2, 1926, Sheppard et al. U.S. Patent 1,623,499, issued April 5, 1927, and Sheppard et al. U.S. Patent 2,410,689, issued November 5, 1946.

The emulsions can also be treated with salts of the noble metals such as ruthenium, rhodium, palladium, iridium, and platinum. Representative compounds are ammonium chloropalladate, potassium chloroplatinate, and sodium chloropalladite, which are used for sensitizing in amounts below that which produces any substantial fog inhibition, as described in Smith and Trivelli U.S. Patent 2,448,060, issued August 31, 1948, and as antifoggants in higher amounts, as described in Trivelli and Smith U.S. Patents 2,566,245, issued August 28, 1951 and 2,- 566,263, issued August 28, 1951.

The emulsions can also be chemically sensitized with gold salts as described in Waller et al. U.S. Patent 2,399,- 083, issued April 23, 1946, or stabilized with gold salts as described in Damschroder U.S. Patent 2,597,856, issued May 27, 1952, and Yutzy and Leermakers U.S. Patent 2,597,915, issued May 27, 1952. Suitable compounds are potassium chloroaurite, potassium aurithiocyanate, potassium chloroaurate, auric trichlon'de and 2- aurosulfobenzothiazole methochloride.

The emulsions can also be chemically sensitized with reducing agents such as stannous salts (Carroll U.S. Patent 2,487,850, issued November 15, 1949), polyamines, such as diethylene triamine (Lowe and Jones U.S. Patent 2,- 518,698, issued August 15, 1950), polyamines, such as spermine (Lowe and Allen U.S. Patent 2,521,925, issued September 12, 1950), or bis(fi-aminoethyl) sulfide and its water-soluble salts (Lowe and Jones U.S. Patent 2,521,- 926, issued September 12, 1950).

The emulsions can also be optically sensitized with cyanine and merocyanine dyes, such as those described in Brooker U.S. Patents 1,846,301, issued February 23, 1932; 1,846,302, issued February 23, 1932; and 1,942,- 854, issued January 9, 1934; White U.S. Patent 1,990,- 507, issued February 12, 1935; Brooker and White U.S. Patents 2,112,140, issued March 22, 1938; 2,165,338, issued July 11, 1939; 2,493,747 issued January 10, 1950, and 2,739,964, issued March 27, 1956; Brooker and Keyes U.S. Patent 2,493,748, issued January 10, 1950; Sprague U.S. Patents 2,503,776, issued April 11, 1950, and 2,- 519,001, issued August 15, 1950; Heseltine and Brooker U.S. Patent 2,666,761, issued January 19, 1954; Heseltine U.S. Patent 2,734,900, issued February 14, 1956; Van Lare U.S. Patent 2,739,149, issued March 20, 1956; and Kodak Limited British Patent 450,958, accepted July 15, 1936.

The emulsions can also be stabilized with the mercury compounds of Allen, Byers and Murray U.S. Patent 2,- 728,663, issued December 27, 1955; Carroll and Murray U.S. Patent 2,728,664, issued December 27, 1955; and Leubner and Murray U.S. Patent 2,728,665, issued December 27, 1955; the triazoles of Heimbach and Kelly U.S. Patent 2,444,608, issued July 6, 1948; the azaindenes of Heimbach and Kelly U.S. Patents 2,444,605 and 2,- 444,606, issued July 6, 1948; Heimbach US. Patents 2,- 444,607, issued July 6, 1948, and 2,450,397, issued September 28, 1948; Heimbach and Clark U.S. Patent 2,444,- 609, issued July 6, 1948; Allen and Reynolds U.S. Patents 2,713,541, issued July 19, 1955, and 2,743,181, issued April 24, 1956; Carroll and Beach U.S. Patent 2,716,062, issued August 23, 1955; Allen and Beilfuss U.S. Patent 2,735,769, issued February 21, 1956; Reynolds and Sagal U.S. Patent 2,756,147, issued July 24, 1956; Allen and Sagura U.S. Patent 2,772,164, issued November 27, 1956, and those disclosed by Birr in Z. wiss. Phot., vol. 47, 1952, pages 228; the disulfides of Kodak Belgian Patent 569,317, issued July 31, 1958; the quaternary benzothiazolium compounds of Brooker and Stand U.S. Patent 2,- 131,038, issued September 27, 1938, or the polymethylene bias-benzothiazolium salts of Allen and Wilson U.S. Patent 2,694,716, issued November 16, 1954 (e.g., decamethylene-bis-benzothiazolium perchlorate); or the zinc and cadmium salts of Jones U.S. Patent 2,839,405, issued June 17, 1958; and the carboxymethylmercapto compounds of Murray, Reynolds and Van Allan U.S. Patent 2,819,965, issued January 14, 1958.

The emulsions may also contain speed increasing compounds of the quaternary ammonium type of Carroll U.S. Patent 2,271,623, issued February 3, 1942; Carroll and Allen U.S. Patent 2,288,226, issued June 30, 1942; and Carroll and Spence U.S. Patent 2,334,864, issued November 23, 1943; and the polyethylene glycol type of Carroll and Beach U.S. Patent 2,708,162, issued May 10, 1955; or the thiopolymers of Graham and Sagal U.S. application Serial No. 779,839, filed December 12, 1958, or Dann and Chechak U.S. application Serial No. 779,874, filed December 12, 1958, or the quaternary ammonium salts and polyethylene glycols of Piper U.S. Patent 2,886,437, issued May 12, 1959.

The emulsions may contain a suitable gelatin plasticizer such as glycerin; a dihydroxy alkane such as 1,5-pentane diol as described in Milton and Murray U.S. application Serial No. 588,951, filed June 4, 1956; an ester of an ethylene bis-glycolic acid such as ethylene bis(methyl glycolate) as described in Milton U.S. application Serial No. 662,564, filed May 31, 1957 (now U.S. Patent 2,904,- 434, issued September 15, 1959); bis-(ethoxy diethylene glycol) succinate as described in Gray U.S. application Serial No. 604,333, filed August 16, 1956 (now U.S. Patent 2,904,854, issued June 14, 1960), or a polymeric hydrosol as results from the emulsion polymerization of a mixture of an amide of an acid of the acrylic acid series, an acrylic acid ester and a styrene-type compound as described in Tong U.S. Patent 2,852,386, issued September 16, 1958. The plasticizer may be added to the emulsion before or after the addition of a sensitizing dye, if used.

The emulsions may be hardened with any suitable hardener for gelatin such as formaldehyde; a halogensubstituted aliphatic acid such as mucobromic acid as described in White U.S. Patent 2,080,019, issued May 11, 1937; a compound having a plurality of acid anhydride groups such as 7,8-diphenylbicyclo (2,2,2)-7-octene-2,3,

5,6-tetra-carboxylic dianhydride, or a dicarboxylic or a disulfonic acid chloride such as terephthaloyl chloride or naphthalene-l,S-disulfonyl chloride as described in Allen and Carroll U.S. Patents 2,725,294 and 2,725,295, both issued November 29, 1955; a cyclic 1,2-diketone such as cyclopentane-1,2-dione as described in Allen and Byers U.S. Patent 2,725,305, issued November 29, 1955; a bisester of methane-sulfonic acid such as 1,2-di-(methanesulfonoxy)-ethane as described in Allen and Laakso U.S. Patent 2,726,162, issued December 6, 1955; 1,3-dihydroxymethylbenzimidazol-Z-one as described in July, Knott and Pollak U.S. Patent 2,732,316, issued January 24, 1956; a dialdehyde or a sodium bisulfite derivative thereof, the aldehyde groups of which are separated by 23 carbon atoms, such as ,B-methyl glutaraldehyde bis-sodium bisulfite as described in Allen and Burness U.S. patent application Serial No. 556,031, filed December 29, 1955 (now abandoned); a bis-aziridine carboxamide such as trimethylene bis(1-aziridine carboxamide) as described in Allen and Webster U.S. patent application Serial No. 599,891, filed July 25, 1956 (now U.S. Patent 2,950,197, issued August 23, 1960); or 2,3-dihydroxy dioxane as described 10 in J effreys U.S. Patent 2,870,013, issued January 20, 1959.

The emulsions may contain a coating aid such as saponin; a lauryl or oleyl monoether of polyethylene glycol as described in Knox and Davis U.S. Patent 2,831,766, issued April 22, 1958; a salt of a sulfated and alkylated polyethylene glycol ether as described in Knox and Davis U.S. Patent 2,719,087, issued September 27, 1955; an acylated alkyl taurine such as the sodium salt of N-oleoyl- N-methyl taurine as described in Knox, Twardokus and Davis U.S. Patent 2,739,891, issued March 27, 1956; the reaction product of a dianhydride of tetracarboxybutane with an alcohol or an aliphatic amine containing from 8 to 18 carbon atoms which is treated with a base, for example, the sodium salt of the monoester of tetracarboxybutane as described in Knox, Stenberg and Wilson U.S. Patent 2,843,487, issued July 15, 1958; a water-soluble maleopimarate or a mixture of a water-soluble maleopimarate and a substituted glutamate salt as described in Knox and Fowler U.S. Patent 2,823,123, issued February 11, 1958; an alkali metal salt of a substituted amino acid such as disodium N-(carbo-ptert. octylphenoxypentaethoxy)-glutamate as described in Knox and Wilson U.S. patent application Serial No. 600,679, filed July 30, 1956; or a sulfosuccinamate such as tetrasodium N-(1,2-dicarboxyethyl)-N-octadecyl sulfosuccinamate or N-lauryl disodium sulfosuccinamate as described in Knox and Stenberg U.S. patent application Serial No. 691,125, filed October 21, 1957.

The addenda which we have described may be used in various kinds of photographic emulsions. In addition to being useful in X-ray and other nonoptically sensitized emulsions they may also be used in orthochromatic, panchromatic, and infrared sensitive emulsions. They may be added to the emulsion before or after any sensitizing dyes which are used. Various silver salts may be used as the sensitive salt such as silver bromide, silver iodide, silver chloride, or mixed silver halides such as silver chlorobromide or silver bromoiodide. The agents may be used in emulsions intended for color photography, for example, emulsions containing color-forming couplers or emulsions to be developed by solutions containing couplers or other color-generating materials, emulsions of the mixed-packet type, such as described in Godowsky U.S. Patent 2,698,794, issued January 4, 1955; or emulsions of the mixed-grain type, such as described in Carroll and Hanson U.S. Patent 2,592,243, issued April 8, 1952. These agents can also be used in emulsions which form latent images predominantly on the surface of the silver halide crystal or in emulsions which form latent images predominantly inside the silver halide crystal, such as those described in Davey and Knott U.S. Patent 2,592,250, issued April 8, 1952.

These may also be used in emulsions intended for use in diffusion transfer processes which utilize the undeveloped silver halide in the nonimage areas of the negative to form a positive by dissolving the undeveloped silver halide and precipitating it on a receiving layer in close proximity to the original silver halide emulsion layer. Such processes are described in Rott U.S. Patent 2,352,- 014, issued June 20, 1944, and Land U.S. Patents 2,584,- 029, issued January 29, 1952; 2,698,236, issued December 28, 1954, and 2,543,181, issued February 27, 1951; and Yackel et al. U.S. patent application Serial No. 586,- 705, filed May 23, 1956. They may also be used in color transfer processes which utilize the diifusion transfer of an image-wise distribution of developer, coupler or dye, from a light-sensitive layer to a second layer, while the two layers are in close proximity to one another. Color processes of this type are described in Land U.S. Patents 2,559,643, issued July 10, 1951, and 2,698,798, issued January 4, 1955; Land and Rogers Belgian Patents 554,- 933 and 554,934, granted August 12, 1957; International Polaroid Belgian Patents 554,212, granted July 16, 1957, and 554,935, granted August 12, 1957; Yutzy U.S. Patent 2,756,142, granted July 24, 1956, and Whitmore and 1 l Mader US. patent application Serial No. 734,141; filed May 9, 1958.

In the preparation of the silver halide dispersions employed for preparing silver halide emulsions, there may be employed as the dispersing agent for the silver halide in its preparation, gelatin or some other colloidal material such as colloidal albumin, a cellulose derivative, or a synthetic resin, for instance, a polyvinyl compound. Some colloids which may be used are polyvinyl alcohol or a hydrolyzed polyvinyl acetate as described in Lowe US. Patent 2,286,215, issued June 16, 1942; a far hydrolyzed cellulose ester such as cellulose acetate hydrolyzed to an acetyl content of 1926% as described in US. Patent 2,327,808 of Lowe and Clark, issued August 24, 1943; a water-soluble ethanolamine cellulose acetate as described in Yutzy US. Patent 2,322,085, issued June 15, 1943; 3. polyacrylamide having a combined acrylamide content of 15-20% and a specific viscosity of 0.09-0.225 or an imidized polyacrylamide having a combined acrylimide content of 30-60%, a combined acrylic acid content of 4 12% and a specific viscosity of 25-15 as described in Lowe, Minsk and Kenyon US. Patent 2,541,474, issued February 13, 1951; zein as described in Lowe US. Patent 2,563,791, issued August 7, 1951; a vinyl alcohol polymer containing urethane carboxylic acid groups of the type described in Unruh and Smith US. Patent 2,768,154, issued October 23, 1956; or containing cyano'acetyl groups such as the vinyl alcohol-vinyl cyanoacetate copolymer as described in Unruh, Smith and Priest US. Patent 2,808,- 311, issued October 1, 1957; or a polymeric material which results from polymerizing a protein or a saturated acrylated protein with a monomer having a vinyl group as described in US. Patent 2,852,382, of Illingsworth, Dann and Gates, issued September 16, 1958.

If desired, compatible mixtures of two or more of these colloids may be employed for dispersing the silver halide in its preparation. Combinations of these antifoggants, sensitizers, hardeners, etc., may be used.

The sensitizing compounds of our invention can be used both in emulsions intended for black-and-white photography, or emulsions intended for color photography. When used for this latter purpose, they can be used in emulsions containing color-forming compounds or couplers, or they can be used in emulsions which are to be color-developed in developers containing the colorforming compounds or couplers. In either type of color photography, the particular color-forming compounds or couplers react with the oxidation products of color developers (particularly phenylenediamine developers) to provide subtractively-colored images. The color-forming compounds can be of the customary types employed in color photography, such as pyrazolone couplers for formation of the magenta image, phenolic couplers for formation of the cyan image and open-chain compounds containing a reactive methylene group for formation of the yellow image. Such couplers can be of the type which can be dispersed in a high-boiling, crystalloidal compound, which can be used as a vehicle for incorporating the color-forming compound in the photographic emulsion, or such couplers can be of the fat-tail varieties (see, for example, F.I.A.T., Final Report, No. 721 for examples thereof) which can be dispersed in the photographic silver halide emulsions. Both of these types of couplers are characterized by non-diffusing properties from the particular silver halide emulsions in which they are incorporated. The couplers or color-forming compounds can be incorporated in the silver halide emulsions by any of the common methods known to those skilled in the art.

Typical color-forming compounds or couplers which are useful in color photography, according to our invention, include the following:

COUPLERS PRODUCING CYAN IMAGES 5-(p-amylphenoxybenzenesulfonamino) -1-naphthol 5- N-benzyl-N-naphthalene sulfonamino) l-naphthol 5- (n-benzyl-N-nwalerylamino) -l-naphthol 5-caproylamino-1-naphthol 2-chloro-5-(N-n-valeryl-N p isopropylbenzylamino) 1- naphthol 2,4-dichloro-5-(p-nitrobenzoyl-fl-o hydroxyethylamino) l-naphthol 2,4-dichloro-5-palmitylamino-l-naphthol 2,2'-dihydroxy-5 ,5 '-dibromostilbene 5 -diphenylethersulfonamido-l-naphthol 1-hydroxy-2-(N-isoamyl-N-phenyl)naphthamide l-hydroxy-Z-(N-p-sec. amylphenyl)naphthamide 8-hydroxy-1-a-naphthoyl-1,2,3,4-tetrahydroquinoline 2-lauryl-4-chlorophenol 1-naphthol-2-carboxylic-a-naphthalide 1-naphthol-S-sulfo-cyclohexylamide 5 -phenoXyacetamino-1-naphthol 5 -flphenylpropionylamino-1-naphthol Monochlor-S-(N yphenylpropyl-N p sec. amylbenzoylamino)-1-naphthol Z-acetylamino-S-methylphenol 2-benzoylamino-3,S-dimethylphenol 2-tx(p-tert. amylphenoxy)n-butyrylamino-S-methylphenol 6-{'y-{4-['y-(2,4 di tert. amylphenoxy)butyramidoJphenoxy} acetamido}-2,4-dichloro-3 -methylphenol 1-hydroxy-2- 6-(2,4-di-tert. amylphenoxy) -n butyl] naph.

thamide Z-oc (-p-tert. amylphenoxy) -n-butyrylamino 4 chloro 5- methylphenol 2-(p-tert. amylphenoXy-p-benzoyl)amino 4 chloro 5'- methylphenol 2-(4"-tert. amyl-3phenoxybenzoylamino)-3,5 dimethyll-phenol Z-phenylacetylaminc-4-chloro-S-methylphenol 2-benzoylamino-4-chloro-5-methylphenol 2-anilinoacetylamino-4-chloro'5-methylphenol 2-{4- Ot- 4"tert. amylphcnoxy) -n-butyrylamino] benzoylamino}-4-chloro-5-methylphenol 2-[4,3"-(4'-tert. amylphenoxyl)benzoylaminoJbenzoylamino-4-chloro-5-methylphen0l Z-p-nitrobenzoylamino-4-chloro-S-methylphenol Z-m-aminobenzoyl-4-chloro-5-methylphenol Z-acetamino-4-chloro-S-methylphenol 2(4-sec. amylbenzamino)-4-chloro-5-methylphenol 2(4'-n-amyloxybenzamino)-4-chloro-5-methylphenol 2(4-phenoxybenzoylamino)phenol 2(4-tert. amyl-3-phenoxybenzoylamino) phenol 2- [ll-(4 4C111. butylphenoxy) propionylamino] phenol 2-[a-(4'-t1t. amyl) phenoxypropionylamino] phenol 2- [N-metl1yl-N-(4-tert. amyl-3'-phenoxybenzoylamino) phenol 2-(4-tert. amyl-3-phenoxybenzoylamino)-3 methyl 1- phenol 2-(4-tert. amyl-3-phenoxybenzoylamino) -6 methyl 1- phenol 2-(4-tert. amyl-3'-phenoxybenzoylamino)-3,6-dimethylphenol 2,6-di(4"-tert. amyl-3'-phenoxybenzoylamino)-1-phenol 2-a- (4'-tert. amylphenoxy) butyrylamino-l-phenol 2(4"-tert. amyl-3-phenoxybenzoylamino)-3,5 dimethyl- 1-phenol 2-[a-(4'-1I't. amylphenoxy) -nbutyrylamino]-5 methyll-phenol 2(4"-tert. amyl-3-phenoxybenzoylamino) 4 chloro lphenol 3-[a(4'-ter. amylphenoxy)-n-butyrylamino] 6 chlorophenol 3-(4"-tert. amyl-3'-phenoxybenzoylamino) phenol 2-[a-(4-tert. amylphenoxy) -n-butyrylamino] 6 chlorophenol 3-[a-(4'-tert. amylphenoxy)-n-butyrylamino] 4 chlorophenol 3-[a-(4-tert. amylphenoxy)-n-butyrylamino] 5 chlorophenol 3-[a-(4'-tert. amylphenoxy)-n-butyrylamino] 2 chlorophenol 13 2-a-(4'-tert. amylphenoxybutyrylamino) --chloropheno1 2-(4-tert. amyl 3 phenoxybenzoylamino) 3 chlorophenol S-benzene sulfonamino-1-naphthol 2,4-dichloro-5'-benzenesulfonamino-l-naphthol 2,4-dichloro-5-(p-toluenesulfonamino-l-naphtho1 5-(1,2,3,4-tetrahydronaphthalene-6-sulfamino) 1 naphthol 2,4-dichloro-5-(4' bromodiphenyl 4 sulfonamino) 1- naphthol 5 (quinoline-S-sulfamino) -1-naphtho1 Any of the acylaminophenol couplers disclosed in Salminen and Weissberger US. Patent 2,423,730, dated July 8, 1947, can be used as couplers for the cyan image,

1 etc.

COUPLERS PRODUCING MAGENTA IMAGES l-p-sec. amylphenyl-3-n-amyl-5-pyrazo1one 2-cy-anoacetyl-5- (p-sec. amylbenzoylamino) coumarone Z-cyanoacetylcoumarone-S-(n-amyl-p-sec. amylsulfanilide) 2-cyanoacetylcoumarone-5-(N-n-amyl-p-tert. amylsulfanilide) 2-cyanoacetylcoumarone-S-SuIfon-N-n-butylanilide 2cyanoacetyl-S-benzoylamino-coumarone Z-cyanoacetylcoumarone-S-sulfondimethylamide 2-cyanoacetylcoumarone-S-sulfon-N-methylanilide Z-cyanoacetylnaphthalene sulfon-N-methylanilide 2-cyanoacetylcoumarone-5- (N-q-phenylpropyl) -p-tert.

'amylsulfonanilide l-p-laurylphenyl-3-methyl-5-pyrazolone 1-B-naphthyl-3-amyl-5-pyrazolone l-p-nitrophenyl-3-n-amyl5-pyrazolone 1-p-phenoxyphenyl-3-n-amyl-5-pyrazolone 1-phenyl-3-n-amyl-5-pyrazolone 1,4-phenylene bis-3-( 1-phenyl-5 -pyrazolone) 1-phenyl-3-acetylamino-S-pyrazolone 1-phenyl-3-propionylamino-5-pyrazolone 1-phenyl-3-n-valery1amino-S-pyrazolone 1-phenyl-3-chloroacetylamino-S-pyrazolone 1-phenyl-3-dichloroacetylamino-S-pyrazolone 1-phenyl-3-benzoylamino-5-pyrazolone 1-phenyl-3-(m-aminobenzoyl) amino-S-pyrazolone l-phenyl-S-(p-sec. amylbenzoylami no) -5-pyrazolone 1-phenyl-3-diamylbenzoylamino-S-pyrazolone 1-phenyl-3-B-n-aphthoylamino-5-pyrazolone 1-phenyl-3-phenylcarbamylamino-S-pyrazolone 1-phenyl-3-palmitylamino-S-pyrazolone 1-phenyl-3-benzenesulfonylamino-5-pyrazolone 1-( p-phenoxyphenyl) -3-(p-tert. amyloxybenzoyl) amino- S-pyrazolone 1-(2',4',6'-tribromophenyl)-3-benzamido-5-pyrazolone 1-(2',4,6'-trichlorophenyl)-3-benzamido-5-pyrazolone 1-( 2,4,6-trichlorophenyl) -3-phenylacetamido-5pyrazolone 1-( 2',4',6'-tribromophenyl) -3 -phenylacetamido-5-pyrazolone 1-(2',4'-dichlorophenyl) -3- [3 (2,4"'-di-tert. amylphenoxyacetamido) benzamido] -5-pyrazolone 1-(2,4,6'-trichlorophenyl) -3- [3 (2",4"-di-tert. amylphenoxyacetamido) benzamido] -5-pyrazolone 1- (2,4,6-tribromophenyl) -3- 3 (2,4"-di-tert. amylphenoxyacetamido) benzamido] -5-pyrazolone 1- (2',4,6-trichlorophenyl) -3- [3-(2,4"'-di-tert, amylphenoxy) -propionamido] -5 -pyr-azolone 1-(2,4',6'-tribromophenyl) -3- [{3- (2',4"-di-tert. amylphenoxy) propionamido] -5-pyrazolone 1-(2',5'-dichloro)-3-[3"-(4-tert. amylphenoxy benzamido1-5-pyrazolone 1- 2,4,6-tribromophenyl) -3- [3 (4"-tert. amylphenoxy) benzamido] -5-pyrazolone 1- 2',5 '-dichlorophenyl -3- [3 "-(2"',4'-di-tert. amylphenoxyacetamido benzamido] -5 -pyrazolone COUPLERS PRODUCING YELLOW IMAGES N-amylp-b enzoylacetamin obenzenesulfonate N- (4-anisoylacetaminobenzenesulfonyl) -N-benzyl-m-toluidine N- (4-benzoylacetaminob enzenesulfonyl) -N-benzy1-m-toluidine N- 4-benzoylacetaminob enzenesulfonyl) -N-n-amyl-p -toluidine N- 4-benzoylacetaminob enzenesulfonyl) -N-benzyla11iline w- (p-B enzoylbenzoyl) acetanilide w-Benzoylacet-2,S-dichloroanilide w-Benzoyl-p-sec. amylacetanilide N,N-di w-benzoylacetyl) -p-phenylenediamine N,N'-diacetoacetamino) diphenyl -oc-{3- oc- 2,4-di-tert.-amylphenoxy) butyramido] benzoyl}- 2-methoxyacetanilide oc-{3- a- (2,4-di-tert.-amylphenoxy) acetamido]benzoyl}- Z-methoxyacetanilide 4,4'-di-( acetoacetamino) -3,3 '-dimethyldiphenyl p,p-di (acetoacetamino diphenylmethane Ethyl-p-benzoylacetaminobenzenesulfonate Nonyl-p-benzoylacetaminobenzenesulfonate N-phenyl-N- (p-acetoacetaminophenyl) urea n-Propyl-p-benzoylacetaminobenzenesulfonate acetoacetpiperidine w-Benzoylacetpiperidide N(w-benzoylacetyl)-1,2, 3 ,4-tetrahydro quinoline N w-benzoylacetyl) morpholine As can be seen by reference to the large number of sensitizers included within our invention, as well as the large number of color-forming compounds which can be employed in combination therewith, a number of combinations of sensitizing compounds and color-forming compounds is possible. In order to determine quickly the effectiveness of a particular combination, it has been found that the screening technique described by Pontius and Thompson in Photo. Sci. Eng, vol. 1, pages 46 1, can be used to get an idea of the potential effectiveness of a given combinationifor use in a photographic color element containing a coupler. This technique does not necessitate the preparation of any coupler dispersions, but the sensitizers can be added to ordinary photographic silver halide emulsions of the type used in black-and-White photography, such: as gelatino-silver-bromiodide emulsions, and the emulsions exposed in an intensity scale sensitometer to daylight quality radiation for a fraction of a second (usually and processed for about 15 minutes in a phenylenediamine color developer, to which has been added 10 g. per liter of H-acid. The pH of this developer is usually adjustedto 10.8 by adding sodium hydroxide. A suitable developer composition for this screening technique is as fol-lows;

Benzyl alcohol cc 10 Sodium hexametaphosphate gram 2.0 Sodium sulfite gram 2.0

Sodium hydroxide gram 3.4 H-acid (1-amino-8-naphthol-3,6 disulfonic acid gram 10.0 4-amino 3 methyl-N-ethyl-N-(fi-methyl sulfonamidoethyl)aniline sulfate gram 8.0 Sodium carbonate monohydrate gram 40.0 Sodium bromide gram 1.5 Sodium thiocyanate "gram-.. 0.2 Benzotriazole gram .03 Water total to 1 liter, pH 10.831

The relative speed, gamma and fog for coatings processed in this manner are given in Table I below.

The following technique was used to determine the effectiveness of our compounds as sensitizers in photographic silver halide emulsions designed for black-andwhite photography.

An ordinary photographic silver bromiodide emulsion containing a sensitizing dye, a sulfur sensitizer of the type mentioned in Sheppard U.S. Patent 1,623,499, mentioned above, and gold sensitized in the manner indicated in U.S. Patent 2,448,060, mentioned above, was divided into several portions. Sensitizing compounds obtained as described above and identified by the example numbers given above, were then added in solutions in an organic solvent, such as ethanol or N,N-dimethylformamide in the amounts indicated in Table I below. The various portions of emulsions were then coated on transparent supports, such as cellulose acetate, and then dried. The dried coatings were exposed for about /35 sec. to daylight quality radiation in an Eastman type Ib sensitometer. The coatings were then developed for about 5 minutes in a photographic developer having the following composition.

DK-SO: G. N-methyl-p-aminophenol sulfate 2.5 Hydroquinone 2.5 Sodium sulfite (dry) 30.0 Sodium 'borate 10.0 Potassium bromide 0.5

Water to make one liter.

The relative speed, as compared with a portion of the same batch of emulsion containing no internal amide sensitizer, and fog for the coatings, were then measured. The results are given in the following table, wherein the compound numbers correspond to the numbers of the above examples:

TABLE I 5' DK-5O Color Developer g./mo1. Compound N 0. Silver Halide Relative Relative Fog Speed Fog Speed The effect of our internal amide sensitizers has been illustrated above with particular reference to ordinary photographic silver bromiodide emulsions, although it is to be understood that other silver halide emulsions can be employed to like advantage.

The following data show the effect produced by adding a sensitizing compound of our invention to an ordinary negative speed silver bromiodide emulsion which had been digested to optimum sensitivity with a mixture of a labile sulfur compound of the type shown in U.S. Patent 1,623,- 499 and a gold compound of the type shown in U.S. Patent 2,448,060. The emulsion had been red-sensitized to that region of the spectrum lying between about 600 and 700 m and it contained a coupler dispersion of one of the color-forming compounds for producing the cyan image upon color development, such as a dispersion of a phenol coupler, e.g., any one of couplers Nos. 1 to 6 of Fierke U.S. Patent 2,801,171 (column 2) in a suitable solvent, such as tri-o-cresylphosphate or dibutylphthalate. In aliquot samples of the same emulsions, there were incorporated internal amide sensitizers as identified in the table. The emulsions were then coated on conventional film supports and dried. The coatings were exposed in an Eastman type Ib sensitometer for 1 sec. to the light emitted by a SOD-watt tungsten lamp adjusted to 6100 K. and further modulated by a Wratten No. 15 filter. The exposed coatings were then processed through a reversal process, such as the following:

The exposed film was developed in a developer having the following compositions:

Sodium hexametaphosphate g 2.0 N-methyl-p-aminophenol sulfate g 6.0 Sodium sulfite, anhydrous g 50.0 Hydroquinone g 6.0 Sodium carbonate monohydrate g 35.0 Potassium bromide g 2.0 Sodium thiocyanate g 1.5

0.5% solution of 6-nitrobenzimidazole nitrate cc 12.0 0.1% solution of potassium iodide cc 10.0 Water to make 1 liter.

The element was then thoroughly washed with Water and treated in a hardening bath having the following composition:

Potassium chrome alum crystals g 30.0 Water to make 1 liter.

The element was thoroughly washed with water and treated for 30 seconds in a solution having the following composition:

Sodium borohydride g 0.25 Sodium hydroxide g 4.0 Water to make 1 liter.

The element was treated in a color developer having the following composition:

Water to make 1 liter.

1 4-amino-N-ethyl-N- (fi-methanesulfonamldo ethy1)-m-to1u1- dlne sesquisulfate monohydrate.

The element was then thoroughly washed with water and treated in a clearing and fixing bath having the following composition:

G. Sodium thiosulfate 150.0 Sodium bisulfite 20.0

Water to make 1 liter.

The element was treated in a bleach bath having the following composition:

Potassium dichromate 5.0 Potassium ferricyanide 70.0 Potassium bromide 20.0

Water to make 1 liter.

The element was again washed and treated once again with the clearing and fixing bath identified above. The element was again washed and treated in a stabilizing bath having the following composition:

Formaldehyde (37% by weight) cc 7.0 Dispersing agent 1 g 0.5 Water to make 1 liter.

1 Such as Triton X-100, i.e., an alkylaryl polyether alcohol (octylphenoxy polyethoxy ethanol).

The following photographic data were obtained:

TABLE II Coating (onccn- T elati e I\ 0. Description tration ADMX. Speed g./n1ole (a) Control Pet. 100 (b) 7,9 Diaza -1,1fi di ydroxy .8 16 115 3,13-ditl iapentadecane-GJO dione (c) Control Tet. 100 (d) 13,15 Diaza -3,6,22,25-ttr0xa- .5 26 105 9,19 ditliapentacosane 12, IG-dione (e) do 1. 0 11 126 (i) Control Ref. 100 (g) 10,12-Diaza-3,19-dioxa 6,16- .5 0 182 ditlial.eneicosane 9,13 dione I 0 08 251 .0 14 289 Control Pei. 100 (k) 9,10- Diaza 2,18 dioxa 5,15 1 145 ditr ranonadecanc-SJZ-dione (l) do 2 08 191 (m) Control F of. 100 (n) 8,10 Diaza 1,17 dihydroxy 1 16 141 4,14dithiaheptadecane-7,1ldione (o) do 2 14 171 While the effect of our sensitizers has been illustrated in Table 11 above with respect to a photographic element having only one color-sensitized layer, it is to be understood that the advantages are also obtained in multilayer films containing a plurality of photographic emulsion layers which have their sensitivity in different regions of the spectrum. The sensitizers are effective not only in red-sensitized emulsions but in emulsions which have their maximum sensitivity in the blue region of the spectrum, or in emulsions which have their maximum sensitivity in the green region of the spectrum.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

What we claim as our invention and desire secured by Letters Patent of the United States is:

1. A photographic silver halide emulsion sensitized with a non-polymeric sensitizer selected from those represented by the following general formula:

R 0 (R SCHfl JHfI JNHMR wherein R represents a member selected from the class consisting of a methylene group, an alkyl-substituted methylene group and a cyclohexylene-p,p-bis methylene group, R represents a member selected from the class consisting of a hydrogen atom and a methyl group, and

R represents a member selected from the class consisting of an alkyl group, an alkoxyalkyl group, an alkoxyalkoxyalkyl group, a hydroxyalkyl group, a hydroxyalkoxyalkyl group, a hydroxyalkoxyalkoxyalkyl group, and an aryloxyalkyl group.

2. A photographic silver halide emulsion as defined in claim 1, said silver halide emulsion being additionally sensitized with a labile sulfur compound.

3. A photographic silver halide emulsion as defined in claim 1, said silver halide emulsion being additionally sensitized with a gold compound.

4. A photographic silver halide emulsion as defined in claim 1, said silver halide emulsion being additionally sensitized with a labile sulfur compound and a gold compound.

5. A photographic silver halide emulsion sensitized with a non-polymeric sensitizer selected from the class represented by the following general formula:

wherein R represents a member selected from the class consisting of a methylene group, an alkyl-substituted methylene group, and a cyclohexylene-p,p'-bis methylene group, R represents a member selected from the class consisting of a hydrogen atom and a methyl group, R represents a member selected from the class consisting of a hydrogen atom, an alkyl group and an aryl group, and n represents a positive integer of from 1 to 4.

6. A photographic silver halide emulsion as defined in claim 5 wherein the silver halide is silver bromiodide.

7. A photographic silver halide emulsion sensitized with a non-polymeric sensitizer selected from the class represented by the following general formula:

(R4NNH( JCHZSCHz( JHCNH)2R wherein R represents a member selected from the class consisting of a methylene group, an alkyl-substituted methylene group and a cyclohexylene-p,p'-bis methylene group, R represents a member selected from the class consisting of a hydrogen atom and a methyl group and R represents a member selected from the class consisting of two hydrogen atoms and a propen-1-ylidene-3 group.

8. A photographic silver halide emulsion as defined in claim 7 wherein the silver halide is silver bromiodide.

9. A photographic silver halide emulsion containing a sensitizing amount of 10,l2-diaza-3,l9-dioxa-6,l6-dithiaheneicosane-9,13-dione.

10. A photographic silver halide emulsion containing a sensitizing amount of l3,l5-diaza-3,6,22,26-tetroxa-9, 19-dithiaheptacosane-l2,l 6-dione.

11. A photographic silver halide emulsion containing a sensitizing amount of 9,10-diaza-2,l8-dioxa-5,l5-dithianonadecane-S,l2-dione.

12. A photographic silver halide emulsion containing a sensitizing amount of 8,l0-diaza-1,l7-dihydroxy-3,l4- dithiaheptadecane-7,1l-dione.

13. A photographic silver halide emulsion containing a sensitizing amount of l0,12-diaza-8,l4-dimethyl-3,l9- dioxa-6,16-dithiaheneicosane-9,13-dione.

References Cited in the file of this patent UNITED STATES PATENTS 2,419,974 Stauffer et al. May 6, 1947 2,640,776 Spence et al. June 2, 1953 2,848,330 Chechak et al Aug. 19, 1958 2,856,427 Bruce et al Oct. 14, 1958 2,927,942 Bikales et al. Mar. 8, 1960 

1. A PHOTOGRAPHIC SILVER HALIDE EMULSION SENSITIZED WITH A NON-POLYMERIC SENSITIZER SELECTED FROM THOSE REPRESENTED BY THE FOLLOWING GENERAL FORMULA:
 3. A PHOTOGRAPHIC SILVER HALIDE EMULSION AS DEFINED IN CLAIM 1, SAID SILVER HALIDE EMULSION BEING ADDITIONALLLY SENSITIZED WITH A GOLD COMPOUND. 